1. Field of the Invention
The present invention is directed to the art of orthotic limb brace joints. In particular, the invention is directed to an improved limb brace joint that rotationally biases the limbs of the wearer.
2. Description of Related Art
Patients with physical conditions or injuries sometimes require the use of an orthotic limb brace, such as an ankle foot orthosis (AFO) or knee ankle foot orthosis (KAFO). These orthoses aid several functions in ambulation, including control of dorsiflexion and plantarflexion in both the stance and swing phases of gait. AFOs also stabilize the ankle in the frontal and transversal planes during balance and gait activities.
Some individuals are afflicted with a condition that does not permit the individual to have full control over muscles that raise and lower the foot. One condition for which an individual does not have full control over the muscles is known as xe2x80x9cdrop footxe2x80x9d. xe2x80x9cDrop footxe2x80x9d occurs when the individual has difficulty in raising the foot (dorsiflexion). Such a condition poses substantial difficulty when walking. The toe or ball of the foot often may not clear the ground while walking. As a result, the individual may end up dragging the foot or may find themselves tripping when walking. Therefore, the individual may stumble and fall while attempting to walk.
Various conventional devices attempt to remedy a drop foot condition by providing an L-shaped ankle and foot orthosis that biases the ankle joint such that the toe or ball portion of the foot is raised. For example, U.S. Pat. No. 5,908,398 to DeToro discloses an adjustable ankle and foot orthosis brace that includes an incrementally adjustable hinge assembly. Also, U.S. Pat. No. 6,102,881 discloses a hinged drop foot brace that
Another conventional dorsiflexion assist ankle joint uses a ball bearing and a spring in a posterior channel of the ankle component that pushes against the posterior edge of the stirrup as the spring is compressed. The spring tension is varied by the use of a set screw at the top of the channel that compresses the spring. The spring must be loose enough to allow the foot to be flat on the floor after heel strike, but tight enough to prevent a foot xe2x80x9cslap.xe2x80x9d The adjustment is also critical to produce enough dorsiflexion during the swing of the foot so that the foot clears the floor without dragging and potentially causing a fall. One problem with this design is that as the spring wears out during its use, it is necessary to continually increase the tension on the set screw. Eventually, the tension is increased to such a high level that the spring breaks inside the channel. The problem is that it is very difficult to repair and/or replace the spring. Additionally, it is impossible for the patient to repair the orthosis and a practitioner must be involved in the repair.
The inventors discovered that a joint is needed that provides for dorsiflexion assist and/or plantarflexion assist in a limb joint brace which is easily repairable by the patient. The joint of the invention solves this and other problems by providing for an easily repairable joint that assists in dorsiflexion and/or plantarflexion.
An exemplary embodiment of a joint in accordance with the invention includes a first longitudinal member rotationally hinged to a second longitudinal member and a band engaging each of the first and second longitudinal members in tension.
Another exemplary embodiment of a joint in accordance with the invention may include multiple bands on the same side of the joint or on opposite sides of the joint. The amount of assist may be adjusted by adding or removing bands and if bands are placed on both sides of the joint, a preferred position for the patient""s limbs may be obtained by selecting bands which balance at the preferred rotational position.
The inventors also devised a band installation tool for the joint of the invention to provide for easy replacement of a faulty and/or failed band.
These and other features and advantages of this invention are described in or are apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings.